Energy management of a video capsule

ABSTRACT

An energy saving device for acquiring in vivo images of the gastro-intestinal tract is provided. The device, such as an autonomous capsule ( 10 ), includes at least one imaging unit ( 12 ), a control unit ( 14 ) connected to the imaging unit, and a power supply ( 24 ) connected to the control unit. The control unit includes a switching unit ( 18, 20 ), and an axial motion detector ( 22 ) connected to the switching unit, disconnects the power supply thereby preventing the acquisition of redundant images.

FIELD OF THE INVENTION

The present invention concerns a management system for controlling theenergy expenditure of autonomous video capsules. More specifically, theinvention is in the field of internal medical inspection of thegastro-intestinal tract.

BACKGROUND OF THE INVENTION

Endoscopic inspection is a common practice in the medical diagnosis ofgastro-intestinal (G.I.) diseases. The video camera used for identifyingobservable irregularities of the internal lining of the G.I. tract isinstalled within an endoscope and progressive scenes are observed bypushing the endoscope inside the tract. The endoscope is a tubulardevice typically containing either a camera with the associated electriccircuits or a fiber-optic image guide. It also includes a light sourceor a light guide, and an electrical conductor for accepting signalsand/or supplying energy. Because the movement of the endoscope headalong the G.I. tract is brought about by a pushing action, themechanical impact associated with such application of force becomeespecially adverse as soon as the head of the endoscope enters a bend.In such bends, the movement of the endoscope is greatly impeded, riskingthe G.I. tract walls, which are susceptible to perforation, and limitingthe method of endoscopic inspection to non-convoluted regions of theG.I. tract.

An in-vivo autonomous video capsule, described in U.S. Pat. No.5,604,531 whose disclosure is incorporated herein by reference, movesalong the G.I. tract by virtue of the natural squeezing action of thetracts walls, thus overcoming the risk of the pushing action, and, inaddition, offering a more convenient method of administering the camera.An additional benefit of the capsule is avoiding the cumbersome aspectsof connecting the intestines of the patient to external appliances. Viathe autonomous capsule, images of the gastro-intestinal tract areobtained without physical connections being made to an energy source oran information drain. An internal power supply energizes the capsule andsupports the illumination image acquisition and radio transmission ofthe information to an external receiver. Because of the considerablelength of the G.I. tract, many images have to be acquired in order tocover the entire length of the tract, this amount of data may beaugmented by redundant images of the same site which are acquired whenthe capsule stops moving or is only barely doing so. Such a taskconsumes a substantial amount of energy, thus potentially becoming alimiting factor in respect of quality and quantity of the set of imagescollected in a single inspection. An additional drawback connected withredundancy of images of a G.I. tract is the effectivity of analysisstage. Once the entire sequence of images is presented to the analyzingphysician, a lengthy process of finding the potential sites of interestensues. Any redundancy existing in such a sequence of images poses adisturbance to analysis procedure.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to provide a device to beincorporated in an autonomous capsule, used for the inspection of theG.I. tract, which minimizes energy expenditure of the imaging unit ofthe capsule.

In accordance with a preferred embodiment of the invention, the capsulewhich obtains in vivo images of the G.I. tract internally, includes atleast one imaging unit: a control unit connected to the imaging unit anda power supply connected to the control unit. The control unit includesa switching unit and an axial motion detector connected to the switchingunit. The axial motion detector detects the axial movement of the deviceand if the axial acceleration is below a pre-determined threshold,disconnects the power supply thereby preventing the acquisition ofredundant images.

Furthermore, in accordance with a preferred embodiment of the invention,the axial motion detector includes an accelerometer, an amplifierconnected to the accelerometer, for amplifying the signal from theaccelerometer and an analyzer connected to the amplifier, for analyzingthe amplified signal. The analyzer includes a comparator for comparingthe analyzed signal with a pre-determined threshold.

In addition, in accordance with a preferred embodiment of the invention,a method for reducing redundant image acquisition of the internalgastro-intestinal tract by an imaging unit residing within a capsulewithin the tract is provided. The method includes the steps of:

detecting the axial motion of the capsule; and

if the detected motion is below a pre-determined threshold,disconnecting the imaging unit.

Furthermore, in accordance with a preferred embodiment of the invention,the method further include a the step of reconnecting the imaging unitif the detected motion is above the pre-determined threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIG. 1 is a schematic block diagram illustration of the structure of amotile video camera residing inside an autonomous capsule.

FIG. 2 is a schematic block diagram illustration showing with detailsthe imaging and the control unit which regulates its power consumption.

FIG. 3 is a block diagram illustration showing in detail the componentsof the motion detector which initiates the sequence of events leadingthe changes in the switching status of the energy supply.

FIG. 4 is an illustration showing the positioning of the autonomouscapsule within the G.I. tract.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to FIG. 1, which shows the schematic structure ofan autonomous capsule 10 containing a control unit 14 for controllingenergy flow from a power supply 24 to the major power consumer in thecapsule which is an imaging unit 12 Minor power consumers 13 are notsubjected to the intervention of unit 14. The power supply 24 of theautonomous capsule, is therefore connected to the imaging unit 12indirectly, thus subjecting the flow of energy to the control exerted bythe control unit 14. The autonomous capsule, containing its own limitedsupply of energy, travels the entire length of the G.I. tract acquiringa potentially large amount of images on the entire length of the tract.Therefore the present invention minimizes the amount of energy consumedconsistent with the acquisition of as much valuable information aspossible.

FIG. 2, to which reference is now made, shows among other units, thedetails of the control unit 14 and imaging unit 12. Other embodiments,providing the same energy economizing effect are included in the presentinvention.

Unit 14 comprises an axial motion detector 22, a switch driver 20, andan on/of switch 18. The axial motion detector 22 detects the movementchanges of the capsule and extracts the axial movement component of thecapsule. If the conditions of a prescribed decision rule have been met,an actuation command is sent to switch driver 20. That is, the switchingunit 18 either connects or disconnects the power supply 24. The imagingunit comprises three major power consumers, namely radio transmitter 27,illuminator (fight emitter) 26, and camera assembly 25. Powerdistributor 16 controls the supply to these consumers.

FIG. 3, to which reference is now being made, is a detailed schematicillustration of the axial motion detector 22. The detector 22 comprisesan axial accelerometer 30, which is connected to an amplifier 32 foramplifying the signal. The enhanced signal is processed by an axialacceleration analyzer 34. The value provided by this analyzer is sent toa threshold acceleration comparator 36 which passes information to theswitch driver 20.

The linear accelerometer 30 is selectively sensitive to accelerations inthe axial direction of the body of the accelerometer. It therefore hasto be physically aligned with the motion axis of the capsule.

The procedure may be described as follows: The output signal from theaccelerometer 30 is first amplified by unit 32, and then provided toanalyzer 34 which determines the actual axial acceleration. Comparator36 compares the acceleration value to a pre-determined threshold valueand decides whether to change the switch. Thus, upon deceleration of thecapsule relative to the G.I. tract, the axial accelerometer wouldindicate a negative acceleration. The magnitude of the signal isanalyzed by unit 34 and a threshold comparison is performed bycomparator 36. If the input is above the threshold value, the powersupply is disconnected via a command from driver 20.

Similarly, if a dormant capsule suddenly starts moving, the signalprovided by the accelerometer 30 is analyzed and compared to thethreshold figure. If the value indicates, the power supply isreconnected to re-activate the imaging unit 12.

The alignment of the motion axis of the capsule is illustrated in FIG.4, which shows some of the structures of the capsule 10. The capsule 10moves along the contracted void 52 of the G.I. tract 56 by the squeezingaction of the walls 50 of the G.I. tract. This causes the longitudinalaxis (referenced 54) of the capsule to align along the local axis 60 ofthe G.I. tract. In order for the axial accelerometer 30 to detect theprogressive motion within the G.I. tract, its longitudinal axis,referenced 56, must be aligned in parallel with the longitudinallyoverlapping axes (54, 60) of the capsule and the G.I. tract,respectively.

False alarms arising from body movements having a component in the axialdirection of the capsule could also actuate an otherwise dormantcapsule, if the signal amplitude is above a predefined threshold occurs.In an alternative embodiment, in order to detect such body movements, anexternal detector can be employed in addition to the internalaccelerometer of the capsule.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed herein above. Rather the scope of the invention is defined bythe claims which follow:

What is claimed is:
 1. A device for acquiring in vivo images of the gastro-intestinal tract, said images forming a sequence of electronic scenes, said device comprising: at least one imaging unit; a control unit connected to said at least one imaging unit, said control unit comprising: a switching unit; and an axial motion detector connected to said switching unit; and a power supply connected to said control unit; wherein said axial motion detector detects the axial movement of the device and if the axial acceleration is below a pre-determined threshold, disconnects said power supply thereby preventing the acquisition of redundant images.
 2. A device according to claim 1 wherein said axial motion detector comprises: an accelerometer; an amplifier connected to said accelerometer, for amplifying said signal from said accelerometer; an analyzer connected to said amplifier, for analyzing said amplified signal.
 3. A device according to claim 2 wherein said analyzer comprises a comparator for comparing said analyzed signal with said pre-determined threshold.
 4. A method for reducing redundant image acquisition of the internal gastro-intestinal tract by an imaging unit residing within a capsule within said tract, the method comprising the steps of: detecting the axial motion of said capsule; and if said detected motion is below a pre-determined threshold, disconnecting said imaging unit.
 5. A method according to claim 4 further comprising the step of reconnecting said imaging unit if said detected motion is above said pre-determined threshold. 